Automatic original feeder for copying machine

ABSTRACT

An automatic feed mechanism for feeding individual sheets in succession from a stack of sheets. A series of blowers decreases the pressure above the uppermost sheet in the stack so that it is raised. The sheet strikes against a series of rotating belts which cause it to move forward. A series of stripper wheels, rotating in the same direction as the belt, is disposed forward of the forwardmost edges of the sheets in the stack and below the belt. In the event more than one sheet have been lifted from the stack and are moving in the forward direction, the stripper wheels bear against the lower surface of the lowermost sheet and force it back into the stack. The force imparted by the stripper wheels is greater than the normal friction force between two adjacent sheets. The stripper wheels have no effect on a single sheet moving in the forward direction because the reverse force imparted by the wheels to this sheet is less than the forward force imparted by the belts.

United States Patent [72] Inventors John A. Van Auken 3,044,770 7/1962 Breuers 271/36 Miami Beach,Fla.; 3,198,514 8/1965 Barbera et a1. 271/l2 Christopher Rush, Ithaca, N.Y.; Fritz A, 3,355,165 1 H1967 Southwell et a1. 271/26 Blank, Hollywood; Lionel Hoffman, Fort OTHER REFERENCES ia Fla; Robe B8110 Des Peres Anderson et a1., IBM Technical Disclosure Bulletin Vol. 6,

N 2, 1 pp No. 833,530 0 963 Class 271 Subclass 12 pgs 32 and 33 [22] Fil d J 1 19 9 Primary Examiner-Joseph Wegbreit {45 patented Oct 1 7 Atrorney-Amster & Rothstein [73] Assignee Copystatics Manufacturing Corporation Mlaml Lakesma' ABSTRACT: An automatic feed mechanism for feeding individual sheets in succession from a stack of sheets. A series of 5 AUTOMATIC ORIGINAL FEEDER FOR COPYING blowers decreases the pressure above the uppermost sheet in MACHINE the stack so that It is raised. The sheet strlkes against a series 21 Claims, 5 Drawing Figs of rotating belts which cause it to move forward. A series of stripper wheels, rotating in the same direction as the belt, IS [52] US. Cl 271/26 R disposed f d f the forwat-dmost edges of the sheets in the [51] 3" 3/12 stack and below the belt. 1n the event more than one sheet [50] Fleld of Search 271/26, 27, have been lifted from the Stack and are moving in the forward 341 30 direction, the stripper wheels bear against the lower surface of [56] Referenc Chd the lowermost sheet and force it back into the stack. The force as I imparted by the stripper wheels is greater than the normal fric- UNITED STATES PATENTS tion force between two adjacent sheets. The stripper wheels 1,241,897 10/ 1917 Ananson 271/9 X have no effect on a single sheet moving in the forward 2,010,586 8/1935 Ehlig 271/37 direction because the reverse force imparted by the wheels to 2,767,982 10/1956 Noon 271/27 X this sheet is less than the forward force imparted by the belts.

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FIG. 3.

INVENTOR-S Joy/v n. wwv AUKl/V CHRISTOPHER RUSH FRITZ n. BLAA/k 74 v BY LID/V5!- HOFFMAN I 19085197 8.4mm

Z2 H wl rm ATTORNEY$ AUTOMATIC ORIGINAL FEEDER FOR COPYING MACHINE This invention relates to copying machines and more particularly to a mechanism for automatically feeding original documents of which copies are required.

In conventional copying machines, those of the electrostatic type, for example, there is generally provided a supply of copy paper. Each time a copy of an original document is to be made, a copy sheet is automatically fed to an exposure station. (In some cases the copy sheet is cut from a roll, while in others it is fed from a stack of sheets.) The original documents themselves from which the copies are made are not generally fed into the machine automatically. Instead, an operator is required to either place each original document face down on a glass plate, or to feed each original document into a pair of input rollers in the original transport section of the machine. Either of these procedures requires the continued participation of the operator during the copying sequence.

It is the general object of this invention to automatically feed one original document after another from a stack of original documents into a copying machine, without the required participation or presence of an operator.

Briefly, in the illustrative embodiment of the invention, the uppermost original document in a stack of originals is lifted slightly by means of suction. Rubber (or other friction) belts are provided for limiting the upward movement of the original document as it is raised. These belts rotate in a direction to move the lifted original document toward the input rollers in the original transport section of the copying machine.

While this arrangement ensures that the upper sheet in the stack moves into the input section of the copying machine, it has been found that the sheet or sheets immediately below the uppermost sheet also sometimes are fed into the original transport section of the copying machine along with the uppermost sheet. This can arise as a result of the various originals sticking together, or the airflow which forces the uppermost sheet against the rubber belts also forcing additional sheets in the same direction.

In accordance with the principles of the invention, a series of stripper wheels is provided below and toward the front of the rubber belts. The stripper wheels rotate in the same direction as that of the belts, but because they are below the original sheets rather than above them, any sheet which passes over them is forced back into the stack. Suppose, for example, that two sheets rise from the stack and are moved forward by the rubber belts, the lower sheet moving forward because it is sticking to the upper sheet. As the two sheets approach the stripper wheels, the stripper wheels bear against the lowermost sheet and force it back into the stack. The only force opposing that of the stripper wheels on the lowermost sheet is the frictional force between the two sheets, which force is insufi'rcient to maintain the lowermost sheet in step with the uppermost sheet in opposition to the stripper wheels. In the case of a single sheet, however, the force moving it in the forward direction arises from the movement of the rubber belts. This force is greater than that applied by the stripper wheels in the reverse direction. Consequently, the uppermost sheet in the stack, the only one bearing against the rubber belts, is moved out of the original feed mechanism by the rubber belts toward the original transport section of the copying machine even though such movement is opposed by the stripper wheels.

It is a feature of the invention, in the illustrative embodiment thereof, to provide a source of suction for lifting the uppermost sheet in a stack, a conveyor mechanism for moving the lifted sheet in a forward direction, and a mechanism disposed underneath the forward path of movement of the sheet for forcing additional sheets below the uppermost sheet to be forced back into the stack.

Further objects, features and advantages of the invention will become apparent upon consideration of the following detailed description in conjunction with the drawing, in which:

FIG. 2 is a sectional view, shown partly broken away, taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged front view, shown partly broken away, of original feed mechanism 20 and shows the drive elements thereof;

FIG. 4 is a top view of feed mechanism 20 with the cover removed; and

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4. FIG. 1 shows an illustrative copying machine 10 having an original transport section 12. In the ordinary use of this machine, an original document 88-1 is fed into guide 14, a pair of rollers (not shown) in the original transport section then moving the original document through the machine to an output tray (not shown). The details of the operation of the copying machine itself are unimportant as far as the present invention is concerned. The present invention concerns feed mechanism 20. The feed mechanism includes a tray 74 for holding a stack of original documents to be copied between two sideplates 92. The feed mechanism serves to continuously supply one sheet after another at the opening of guide 14 of the copying machine. The feed mechanism 20 simply sits on the copying machine as shown most clearly in FIG. 2. It is to be understood that the feed mechanism can be used for purposes other than the automatic feeding of original documents into a copying machine. It can be used wherever a continuous feed of sheets from a stack is required.

The invention is perhaps most clearly understood with reference to FIG. 5. Four blowers 26-1 through 26-4 are provided for directing airflow as shown by arrows 78. The four blowers are distributed across the width of the stack of sheets 88 and serve to lift the uppermost sheet 88-1. Disposed beneath the blowers is a series of rubber belts 64 (see also FIG. 2) and as the uppermost sheet in the stack is pulled up it strikes against the lower parts of the belts. The belts move in the counterclockwise direction in FIG. 5 and as the uppermost sheet in the stack bears against them it is forced to move in the forward direction. The forward edge of the sheet hits a grid network composed of rods 66 and 70, and is deflected downward toward guide 14. It should be noted that the airflow is directed out of the outlet ducts of the blowers in such a way that the uppermost sheet is forced downward toward the front of the feed mechanism. This causes the document to arch slightly to further aid its lifting up toward the rubber belts.

It is possible that one or more sheets directly below the uppermost sheet 88-1 in the stack will also be forced upward by the flow of air, and as a result of the friction between the various sheets might move in the forward direction along with the uppermost sheet. To prevent this double-feed, stripper wheels 84 are provided. These stripper wheels also rotate in the counterclockwise direction as shown in FIG. 5. Each stripper wheel includes a tip 86 preferably made of a material having a high coefficient of friction, e.g., a urethane compound. Each tip is mounted on a foam head 94 for compliance with the original documents. As the stripper wheels rotate, the friction tips bear against the underside of the lowermost sheet 88-2 on top of the stripper wheels, and they force this sheet back into the stack. The force tending to move sheet 88-2 in the forward direction is the frictional force between sheets 88-1 and 88-2, and this force is less than the frictional force generated by the rotating stripper wheels. In the event only one sheet is lifted from the stack, the forward moving force generated by the friction of belts 64 against the upper surface of the sheet is greater than the force in the reverse direction generated by the stripper wheels, and the sheet continues to move in the forward direction.

As soon as one sheet is fed out of the feed mechanism, the next sheet is lifted by the airflow. A continuous succession of sheets is fed into the entrance slot defined by guide 14.

Referring to FIGS. 2-5, motor 32 drives shaft 24. Shaft 24 is connected at one end to shaft 38 by coupler 36. Shaft 38 is extended through the various blowers for driving the blower rotors and vanes 76 as is known in the art. Shaft 24, on the other side of the motor, is connected to pulley 72 (see FIG. 3) around which belt 46 passes. This belt drives pulley 44 which is mounted on shaft 48. Gear 50, also mounted on shaft 48, is thus driven by the motor. Gear 50 drives gear 52 which directly drives shaft 60. A series of belt drive elements 62 is mounted on shaft 60 and these elements are driven in the counterclockwise direction of FIG. 5. A second shaft 28 is provided on which another series of belt drive elements 62 is mounted. The six belts 64 are mounted around the various pairs of belt drive elements and are driven by shaft 60 in the counterclockwise direction of FIG. 5.

A second belt 56 couples pulley 54, connected to gear 52, to pulley 58. This pulley is in turn connected to shaft 68 on which the two stripper wheels 84 are mounted. The stripper wheels are thus driven in the same direction as the rubber belts, counterclockwise in FIG. 5. But because the sheets pass between the rubber belts and the stripper wheels, the belts and wheels apply oppositely directed forces to the sheets.

The overall drive unit is mounted in section 42 of the feed mechanism. This section is mounted on the leftmost side of the unit as shown in FIG. 2. The two sides of the base section 22-1, 22-2 have a configuration to mate with the upper surface of copying machine 10. A grid comprising horizontal rods 66 and vertically inclined rods 70, seen most clearly in FIGS. 2 and 5, form an upper guide for the forward moving sheet. Another series of horizontal rods 82 and a series of bent rods 74 form another grid which serves both as a lower guide for the forward moving sheet and as a forward stop for the entire stack of sheets in the feed mechanism, as seen most clearly in F IG. 5.

Extended across the width of the mechanism are two rods 25, 34 (see FIG. 4) both of which serve to mount the four blowers 26-1 through 26-4. Each blower is provided with a pair of mounting holes at both its front and back through which rods 25 and 34 pass, as seen most clearly in FIG. 5. Separating the blowers on the rods are a series of spacers 30. The details of the mounting of the blowers in the unit will be well understood by those skilled in the art. The blowers are positioned above the rubber belts 64 and serve to suck up air and force it out as shown by arrows 78 in FIG. 5.

As seen most clearly on FIG. 4, the bottom plate 74 of the unit, on which the stack of original documents is placed, is provided with a series of grooves 90 on either side. lnto one groove on each side of the unit an upright guide 92 can be placed to correctly position the stack of paper documents on tray 74. The side guides are placed in selected ones of grooves 90 in accordance with the width of the paper in the stack. Grooves 90 in base plate 74 are designed to accommodate most common paper sizes. (Only two grooves on each side of the unit are shown in FIG. 4 for the sake of clarity; it is to be understood that in practice as many grooves can be used as is desired.)

Feed mechanism 20 preferably operates at a rate slightly slower than that of the copying machine, that is, whenever an original document to be copied is provided by the feed mechanism the copying machine is in a condition to accept it. Since the feed mechanism cannot drive a sheet after its trailing edge has left bells 64, the original transport section of the copying machine should have control of the sheet by this time.

It should also be noted that anything blocking a paper sheet as it leaves feed mechanism 20 will not cause a jam. The sheet will simply slip on the rubber belts.

As described above, the uppermost sheet is lifted by air flowing into the blower intake parts. This lifting operation is aided by the turbulence created by the air leaving the blower exhaust ports in the vicinity of the forward edges of the original stacked documents. The turbulence helps to separate the originals so that the uppermost document is the only one which is lifted. With the uppermost sheet bearing against belts 64 and moving forward, the exhaust ports are blocked from creating the air turbulence at the front of the stack of originals to prevent another sheet from being lifted. In fact, a second sheet may not be lifted until after a first one has cleared the exhaust ports and this prevents one sheet from immediately following the other.

Although the invention has been described with reference to a particular embodiment, and is to be understood that this embodiment is merely illustrative of the application of the principles of the invention. It is possible, for example, to create the air turbulence for lifting the topmost sheet with the use of blowers situated at the bottom of the unit for blowing air upward. Placing the (suction) blowers at the top is preferable, however, because, in the case of blockage of a sheet, the sheet tends to cut off the airflow to efiectively halt the entire operation. Thus, it is to be understood that numerous modifications may be made in the illustrative embodiment of the invention and other arrangements may be devised without departing from the spirit and scope of the invention.

What is claimed is:

1. An automatic feed mechanism for feeding individual sheets in succession from a vertically disposed stack of substantially horizontal sheets comprising means for lifting the uppermost sheet in said stack, means for imparting a force in the forward direction to the uppermost sheet lifted from said stack, and positive means for imparting a force in the reverse direction to the lowermost sheet in any group of sheets which may have been lifted from said stack and are moving in the forward direction, the force imparted in said reverse direction being greater than the normal friction force between two adjacent sheets and being less than the force imparted in the forward direction to the uppermost lifted sheet.

2. An automatic feed mechanism in accordance with claim 1 wherein said lifting means includes means for creating a decreased air pressure above the uppermost sheet in said stack relative to the sheets underneath said uppermost sheet.

3. An automatic feed mechanism in accordance with claim 1 wherein said forward force-imparting means includes rotating means for bearing against the top surface of the uppermost sheet lifted from said stack and for moving said uppermost sheet in the forward direction.

4. An automatic feed mechanism in accordance with claim 3 wherein said reverse force-imparting means includes rotating means disposed in a position forward of the forwardmost edges of the sheets in said stack and below said forward forceimparting means, said reverse force-imparting means rotating in the same direction as said forward force-imparting means and bearing against the lower surface of the lowest sheet in any group of sheets moving in the forward direction.

5. An automatic feed mechanism in accordance with claim 4 further including a single motor for energizing said lifting means, for driving said forward force-imparting means and for driving said reverse force-imparting means.

6. An automatic feed mechanism in accordance with claim 2 wherein said forward force-imparting means includes rotating means for bearing against the top surface of the uppermost sheet lifted from said stack and for moving said uppermost sheet in the forward direction, and said reverse force-imparting means includes rotating means disposed in a position forward of the forwardmost edges of the sheets in said stack and below said forward force-imparting means, said reverse forceimparting means rotating in the same direction as said forward force-imparting means and bearing against the lower surface of the lowest sheet in any group of sheets moving in the forward direction.

7, An automatic feed mechanism in accordance with claim 6 wherein said forward force-imparting means includes a plurality of rotating belts and said reverse force-imparting means includes a plurality of stripper wheels.

8. An automatic feed mechanism in accordance with claim 6 further including guide means for forcing the leading edge of the uppermost sheet in any group of sheets moving in the forward direction to be directed down toward and out of the bottom of the mechanism.

9. An automatic feed mechanism in accordance with claim 8 wherein said lifting means further include means for creating an increased air pressure above the uppermost sheet in a group of sheets moving in the forward direction at a position forward of the forward edges of the sheets in said stack for arching the uppermost sheet lifted by said lifting means.

10. An automatic feed mechanism for feeding individual sheets in succession from a vertically disposed stack of substantially horizontal sheets comprising means for imparting a force in the forward direction to the uppermost of one of the sheets in said stack, and positive means for imparting a force in the reverse direction to the lowermost sheet in any group of sheets which are moving in the forward direction, said reverse force-imparting means being operative to force said lowermost sheet back into said stack, the force imparted in said reverse direction being greater than the normal friction force between two adjacent sheets moving in the forward direction and being less than the force imparted in the forward direction to said uppermost sheet.

11. An automatic feed mechanism in accordance with claim wherein said forward force-imparting means includes rotating means for hearing against the top surface of the uppermost sheet in said stack and for moving said uppermost sheet in the forward direction, and said reverse force-imparting means includes rotating means disposed in a position forward of the forwardmost edges of the sheets in said stack and below said forward force-imparting means, said reverse force-imparting means rotating in the same direction as said forward force-imparting means and bearing against the lower surface of the lowest sheet in any group of sheets moving in the forward direction.

12. An automatic feed mechanism in accordance with claim 11 wherein said forward force-imparting means includes a plurality of rotating belts and said reverse force-imparting means includes a plurality of stripper wheels.

13. An automatic feed mechanism for feeding individual sheets in succession from a vertically disposed stack of substantially horizontal sheets comprising blower means for lifting the uppermost sheet in said stack, transport means disposed above the uppermost sheet in said stack, means for rotating said transport means to move in the forward direction a sheet lifted by said blower means against said transport means, and stripper means disposed in a position forward of the forward edges of the sheets in said stack and below said transport means for bearing against the lower surface of the lowest sheet in any group of sheets moving in the forward direction.

14. An automatic feed mechanism in accordance with claim 13 wherein said transport means includes a plurality of belts and further including means for rotating said stripper means in the same direction as said transport means.

15. An automatic feed mechanism in accordance with claim 14 further including a single motor for driving said blower means, said transport means and said stripper means.

16. An automatic feed mechanism for feeding individual sheets substantially horizontally and in succession from a stack of sheets comprising a tray for supporting said stack in position for the individual feeding of the uppermost sheet in succession from the top of said stack, a conveyor disposed above said tray and including at least a lower and substantially horizontal run spaced above said stack, means for driving said conveyor such that successive uppermost sheets when lifted into frictional contact with said lower run are fed by a feeding force in a forward direction, means for creating a decreased air pressure above said tray such that successive uppermost sheets in said stack are lifted against the force of gravity into frictional contact with said lower run of said conveyor for feed in said forward direction and positive means for imparting a separating force in the reverse direction to the lowermost sheet in any group of sheets which may have been inadvertently lifted from said stack and moved in said forward direction, said departing force being greater than the normal frictional force between two adjacent sheets and being less than said feeding force imparted in said forward direction to successive uppermost sheets.

17. An automatic feed mechanism according to claim 16 wherein the means for creating a decreased air pressure includes an air blower having at least one air inlet duct disposed within the width of said tray and conveyor, said air inlet duct being spaced from the forward end of said conveyor and terminating above said lower run of said conveyor.

18. An automatrc feed mechanrsm according to clarm 17 wherein said air blower has an air outlet duct disposed within the width of said tray and conveyor, said air outlet duct extending toward said forward end of said conveyor and being arranged to create a downward airflow for deflecting successive uppermost sheets moving in said forward direction.

19. An automatic feed mechanism according to claim 16 wherein the means for creating a decreased air pressure includes a plurality of air 'blowers having a corresponding plurality of air inlet ducts disposed at spaced locations across the width of said tray and conveyor, said air inlet ducts being spaced from the forward end of said conveyor and terminating in a common horizontal plane above said lower run of said conveyor.

20. An automatic feed mechanism according to claim 17 wherein said plurality of air blowers have a corresponding plurality of air outlet ducts disposed at spaced locations across the width of said tray and conveyor, said an outlet ducts extending toward said forward end of said conveyor and being arranged to create downward airflows for deflecting successive uppermost sheets moving in said forward direction.

21. An automatic feed mechanism according to claim 16 wherein the means for imparting said separating force includes a plurality of stripper rollers disposed at spaced locations across the width of said tray contiguous to and spaced forwardly thereof, said stripper rollers being spaced from and below said lower run of said conveyor and dimensioned to engage the lowermost sheet in any group of sheets which may have been lifted from said stack. 

1. An automatic feed mechanism for feeding individual sheets in succession from a vertically disposed stack of substantially horizontal sheets comprising means for lifting the uppermost sheet in said stack, means for imparting a force in the forward direction to the uppermost sheet lIfted from said stack, and positive means for imparting a force in the reverse direction to the lowermost sheet in any group of sheets which may have been lifted from said stack and are moving in the forward direction, the force imparted in said reverse direction being greater than the normal friction force between two adjacent sheets and being less than the force imparted in the forward direction to the uppermost lifted sheet.
 2. An automatic feed mechanism in accordance with claim 1 wherein said lifting means includes means for creating a decreased air pressure above the uppermost sheet in said stack relative to the sheets underneath said uppermost sheet.
 3. An automatic feed mechanism in accordance with claim 1 wherein said forward force-imparting means includes rotating means for bearing against the top surface of the uppermost sheet lifted from said stack and for moving said uppermost sheet in the forward direction.
 4. An automatic feed mechanism in accordance with claim 3 wherein said reverse force-imparting means includes rotating means disposed in a position forward of the forwardmost edges of the sheets in said stack and below said forward force-imparting means, said reverse force-imparting means rotating in the same direction as said forward force-imparting means and bearing against the lower surface of the lowest sheet in any group of sheets moving in the forward direction.
 5. An automatic feed mechanism in accordance with claim 4 further including a single motor for energizing said lifting means, for driving said forward force-imparting means and for driving said reverse force-imparting means.
 6. An automatic feed mechanism in accordance with claim 2 wherein said forward force-imparting means includes rotating means for bearing against the top surface of the uppermost sheet lifted from said stack and for moving said uppermost sheet in the forward direction, and said reverse force-imparting means includes rotating means disposed in a position forward of the forwardmost edges of the sheets in said stack and below said forward force-imparting means, said reverse force-imparting means rotating in the same direction as said forward force-imparting means and bearing against the lower surface of the lowest sheet in any group of sheets moving in the forward direction.
 7. An automatic feed mechanism in accordance with claim 6 wherein said forward force-imparting means includes a plurality of rotating belts and said reverse force-imparting means includes a plurality of stripper wheels.
 8. An automatic feed mechanism in accordance with claim 6 further including guide means for forcing the leading edge of the uppermost sheet in any group of sheets moving in the forward direction to be directed down toward and out of the bottom of the mechanism.
 9. An automatic feed mechanism in accordance with claim 8 wherein said lifting means further include means for creating an increased air pressure above the uppermost sheet in a group of sheets moving in the forward direction at a position forward of the forward edges of the sheets in said stack for arching the uppermost sheet lifted by said lifting means.
 10. An automatic feed mechanism for feeding individual sheets in succession from a vertically disposed stack of substantially horizontal sheets comprising means for imparting a force in the forward direction to the uppermost of one of the sheets in said stack, and positive means for imparting a force in the reverse direction to the lowermost sheet in any group of sheets which are moving in the forward direction, said reverse force-imparting means being operative to force said lowermost sheet back into said stack, the force imparted in said reverse direction being greater than the normal friction force between two adjacent sheets moving in the forward direction and being less than the force imparted in the forward direction to said uppermost sheet.
 11. An automatic feed mechanism in accordance with claim 10 wherein said forward force-imparting means includes rotAting means for bearing against the top surface of the uppermost sheet in said stack and for moving said uppermost sheet in the forward direction, and said reverse force-imparting means includes rotating means disposed in a position forward of the forwardmost edges of the sheets in said stack and below said forward force-imparting means, said reverse force-imparting means rotating in the same direction as said forward force-imparting means and bearing against the lower surface of the lowest sheet in any group of sheets moving in the forward direction.
 12. An automatic feed mechanism in accordance with claim 11 wherein said forward force-imparting means includes a plurality of rotating belts and said reverse force-imparting means includes a plurality of stripper wheels.
 13. An automatic feed mechanism for feeding individual sheets in succession from a vertically disposed stack of substantially horizontal sheets comprising blower means for lifting the uppermost sheet in said stack, transport means disposed above the uppermost sheet in said stack, means for rotating said transport means to move in the forward direction a sheet lifted by said blower means against said transport means, and stripper means disposed in a position forward of the forward edges of the sheets in said stack and below said transport means for bearing against the lower surface of the lowest sheet in any group of sheets moving in the forward direction.
 14. An automatic feed mechanism in accordance with claim 13 wherein said transport means includes a plurality of belts and further including means for rotating said stripper means in the same direction as said transport means.
 15. An automatic feed mechanism in accordance with claim 14 further including a single motor for driving said blower means, said transport means and said stripper means.
 16. An automatic feed mechanism for feeding individual sheets substantially horizontally and in succession from a stack of sheets comprising a tray for supporting said stack in position for the individual feeding of the uppermost sheet in succession from the top of said stack, a conveyor disposed above said tray and including at least a lower and substantially horizontal run spaced above said stack, means for driving said conveyor such that successive uppermost sheets when lifted into frictional contact with said lower run are fed by a feeding force in a forward direction, means for creating a decreased air pressure above said tray such that successive uppermost sheets in said stack are lifted against the force of gravity into frictional contact with said lower run of said conveyor for feed in said forward direction and positive means for imparting a separating force in the reverse direction to the lowermost sheet in any group of sheets which may have been inadvertently lifted from said stack and moved in said forward direction, said departing force being greater than the normal frictional force between two adjacent sheets and being less than said feeding force imparted in said forward direction to successive uppermost sheets.
 17. An automatic feed mechanism according to claim 16 wherein the means for creating a decreased air pressure includes an air blower having at least one air inlet duct disposed within the width of said tray and conveyor, said air inlet duct being spaced from the forward end of said conveyor and terminating above said lower run of said conveyor.
 18. An automatic feed mechanism according to claim 17 wherein said air blower has an air outlet duct disposed within the width of said tray and conveyor, said air outlet duct extending toward said forward end of said conveyor and being arranged to create a downward airflow for deflecting successive uppermost sheets moving in said forward direction.
 19. An automatic feed mechanism according to claim 16 wherein the means for creating a decreased air pressure includes a plurality of air blowers having a corresponding plurality of air inlet ducts disposed at spaced locations across the wIdth of said tray and conveyor, said air inlet ducts being spaced from the forward end of said conveyor and terminating in a common horizontal plane above said lower run of said conveyor.
 20. An automatic feed mechanism according to claim 17 wherein said plurality of air blowers have a corresponding plurality of air outlet ducts disposed at spaced locations across the width of said tray and conveyor, said air outlet ducts extending toward said forward end of said conveyor and being arranged to create downward airflows for deflecting successive uppermost sheets moving in said forward direction.
 21. An automatic feed mechanism according to claim 16 wherein the means for imparting said separating force includes a plurality of stripper rollers disposed at spaced locations across the width of said tray contiguous to and spaced forwardly thereof, said stripper rollers being spaced from and below said lower run of said conveyor and dimensioned to engage the lowermost sheet in any group of sheets which may have been lifted from said stack. 